R saner



1954 w. R. SANER 2,698,242

Pl-lOTOGRAPl-IIC ELEMENTS AND PREPARATION THEREOF Filed June 9, 1952 Fig. 1

, ./-Organic polyisocyanale or polyisolhiocyanale L/ Walerpermeable colloid and silver halide v Hydrophobic film base, e.g., cellulose derivative, polyester, etc.

Water-permeable colloid and silver halide Water-permeable colloid, e.g., gelatin Organic polyisocyanale or polyisolhiocyanale Hydrophobic film base, e.g., cellulose derivative, polyesler,elc.

Water-permeable colloid and silver halide Water-permeable colloid, e.g., gelatin Organic polyisocyanale or palyisolhiocyanale Vinylidene chloride-acrylic esler-ilacanic acid copolymer Polyethylene lerephlhalale INVENTOR WILLIAM RUSSELL SANER ATTORNEY United States Patent PHOTOGRAPHIC ELEMENTS AND PREPARATION THEREOF William Russell Saner, Plainfield, N. 1., assignor to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware Application June 9, 1952, Serial No. 292,573 12 Claims. (Cl. 95-9) This invention relates to photographic film elements and to their preparation. More particularly it relates to a process of improving the anchorage between a hydrophobic film base and a colloid silver halide layer. Still more particularly it relates to a process for improving the anchorage between (1) a photographic film base consisting of an oriented polyester film bearing on at least one surface, a substratum coating composed of a copolymer of vinylidene chloride, an acrylic ester and itaconic acid, and (2) a water-permeable colliod layer, and to the resulting photographic film.

Photographic manufacturers are continuously trying to obtain improvements in the anchorage of photographic emulsions to hydrophobic film bases. With the advent of synthetic polymer films the conventional procedures are not always satisfactory. The preparation of photographic films by coating an orientable highly polymeric ester of a dicarboxylic acid and a dihydric alcohol, e. g., a polyethylene terephthalate with an aqueous dispersion of a copolymer of vinylidene chloride, an acrylic acid ester and itaconic acid, then biaxially orienting the coated base and subsequently applying a water-permeable colloid layer is described in Alles and Saner, U. S. app. Ser. No. 151,274, filed March 22, 1950, now U. S. Patent 2,627,088. It has been found that if such copolymer coated polyester film bases are not coated within a short time after the layer of copolymer has dried, the degree of adherence between the base and a subsequently applied waterpermeable colloid layer progressively decreases with the length of time. This is true even when a water-permeable colloid sublayer is applied to the copolymer layer.

Since it is not always possible to correlate the coating of photographic emulsion layers with the manufacture of the film base it is common practice in the manufacturing operations to store rolls of base until needed and to keep an adequate supply on hand. Many different types of emulsions are coated onto the same kind of film base and the coating operations are governed by the demand for particular types of photographic film. Hence, the progressive decrease in adherence upon aging of polyester films is a serious problem to the industry.

The present invention, however, is not limited to the use of poyester film bases which are provided with a vinylidene chloride-acrylic ester-itaconic acid copolymer layer, although that constitutes the preferred embodiment, as the anchorage between water-permeable colloid silver halide emulsion layers and other types of film base can be improved in like manner by applying a layer of an organic polyisocyanate or polyisothiocyanate before applying a water-permeable colloid layer and/or waterpermeable colloid silver halide emulsion layer. Thus the film base or support may consist of a hydrophobic cellulose derivative, e. g., cellulose acetate, cellulose propionate, cellulose acetate propionate, cellulose acetate butyrate, cellulose nitrate, polyvinyl chloride, a superpolyamide (nylon) etc., and such supports which are coated with a copolymer of vinylidene chloride with another polymerizable vinyl compound, e. g., acrylonitrile, isobutylene, styrene, vinyl chloride, vinyl acetate, and methyl methacrylate including the supports described in Alles and Saner U. S. Patent 2,491,023.

An object of this invention is to provide a new process for anchoring colloid silver halide emulsion layers to hydrophobic film supports. Another object of this invention is to provide a process for improving the adherence between photographic film base having a film support composed of an oriented polyester and a substratum coating composed of a copolymer of vinylidene chloride. an acrylic ester and itaconic acid and a water-permeable colloid silver halide emulsion. Yet another object is to 2,698,242 Patented Dec. 28, 1954 "ice provide such a process which can be practiced with the usual equipment of a photographic film manufacturer. A further object is to provide such a process which is economical and utilizes available chemicals. A still further object is to provide photographic elements of the above type which have a novel anchoring substratum. Still other objects will be apparent from the following description of the invention.

The process of this invention in its broader aspects consists in coating a hydrophobic film base with a thin layer of an organic polyisocyanate or polyisothiocyanate and then applying a layer of a water-permeable colloid and/or a Water-permeable silver halide emulsion layer. The organic polyisocyanate or polyisothiocyanate can be applied from a solution in a suitable organic solvent, preferably a volatile solvent which does not have any significant solvent action on the film base, which solution is essentially free from water or anhydrous and which does not react with the isocyanate compound. After drying an aqueous solution of a water-permeable colloid, e. g., gelatin may be applied and then an aqueous dispersion of light-sensitive silver halides in an aqueous solution of a water-permeable colloid, e. g., gelatin is applied to the dry light-insensitive colloid substratum. When latter substratum is eliminated the aqueous dispersion of silver halides can be directly applied to the polyisocyanate or polyisothiocyanate layer. The colloid layer is then heated, e. g., from 50 C. to C.

In the preferred embodiment of the invention an orientable hydrophobic film composed of a polyester of a dicarboxylic acid and a dihydric alcohol of the type described in Carothers U. S. P. 2,071,250 and particularly the high-melting difiicultly soluble, usually microcrystalline, cold-drawing linear, highly polymerized esters of terephthalic acid and glycols of the series HO(CH2)1OH, where n is an integer with the range of 2 to 10, described in Whinfield et al. U. S. P. 2,465,319, is provided with a thin coating of a vinylidene chloride-acrylic ester-itaconic acid copolymer and the coated film is biaxially oriented after the manner described in Alles and Saner U. S. Patent 2,627,088. This film base can then have its copolymersurface coated with a water-permeable colloid and/or water-permeable colloid silver halide emulsion layer.

Film elements of the types described above are shown in the accompanying drawing, which constitutes a part of this specification, wherein:

Fig. 1 is a schematic cross-sectional view of one type of film element of this invention.

Fig. 2 is a schematic cross-sectional view of another type of film element of this invention.

Fig. 3 is a schematic cross-sectional view and yet another type of film element of this invention.

Referring now to Fig. 1 of the drawing. a hydrophobic film base which may be composed of a cellulose derivative, polyester, etc. as described above, is provided with a layer 2 composed of an organic polyisocyanate or polyisothiocyanate which in turn is provided with a layer 3 composed essentially of water permeable colloid and silver halide.

In Figure 2 the film element is like that described in Fig. 1 except that a layer 3 composed of a waterperrneable colloid, e. g., gelatin is interposed between the layer of polyisocyanate or polyisothiocyanate and the water-permeable colloid silver halide emulsion layer.

The film element of Fig. 3 consists of a hydrophobic polyethylene terephthalate film base 1' which is provided with a layer of 2 composed of a vinylidene chlorideacrylic ester-itaconic acid copolymer, which in turn is coated with layer 2 composed of an organic polyisocyanate or polyisothiocyanate. The latter layer in turn supports water-permeable colloid silver halide emulsion layer 3.

The initial relative proportions of monomers used for the preparation of the copolymers of app. Ser. No. 151,274 should be within the following ranges:

The useful acrylic esters which may housed in the copolymers are the alkyl esters of acrylic and methacrylic acids having from 1 to 18 carbon atoms in the alkyl group (e. g., methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, n-dodecyl methacrylate, n-octadecyl methacrylate), methyl acrylate, ethyl acrylate and propyl acrylate; vinyl chloride, acrylonitrile and methacrylonitrile.

The monomers may be copolymerized by various methods. For example, the copolymerization may be conducted in aqueous dispersion containing a catalyst and activator, e. g., ammonium persulfate and meta sodium bisulfite, and an emulsifying and/or dispersing agent. Alternatively, the copolymers of this invention may be prepared by polymerization of the monomeric components in bulk without added diluent, or the monomers may be reacted in appropriate organic solvent reaction media. The total catalyst-activator concentration should generally be kept within a range of about 0.01% to about 2.0% by weight of the monomer charge, and preferably within a range of concentration of 0.1% to 1.0%. Improved solubility and viscosity values are obtained by conducting the polymerization in the presence of mercaptans such as ethyl mercaptan, lauryl mercaptan, tertiary dodecyl mercaptan, etc., which are effective in reducing cross-linking in the copolymer. In general, the mercaptans should be used in concentrations of 0.1% to 5.0% by weight, based on the weight of polymerizable monomers present in the charge.

After drying and at the time it is desired to apply a photographic silver halide emulsion or dispersion to the base described in the two preceding paragraphs the layer of polyisocyanate and polyisothiocyanate and water-permeable colloid and/or water-permeable colloid silver halide dispersions are applied as described above and dried.

. The invention will be further illustrated by the following examples.

Example I Asample of polyethylene terephthalate film, having a melting point above 200 C., and an intrinsic viscosity of approximately 0.50 in a mixture of 2,4,6-trichlorophenol and phenol (70: 100 parts by weight), was coated with an aqueous dispersion of a vinylidene chloride-acrylic esteritaconic acid'copolymer of the type described in Alles and Saner U. S. Patent No. 2,627,088. After drying at 50 C., the film was stretched biaxially about 3 times its original dimensions, and coated with a 1% solution of methylene bis (4-phenylisocyanate) in methylene chloride. After drying at 50 C., a layer of gelatin was applied over the diisocyanate from a 2% aqueous solution and the film was dried at 50 C. and heated at 100 C. for 2 minutes. An aqueous gelatino-bromochloride dispersion containing 5.6% halides, 4% gelatin, and 0.4% formaldehyde (as 35-40% solution) by weight was applied to gelatin substratum. After drying, the anchorage of the gelatinosilver halide layer to the base was good. After exposing the film was processed as follows:

(1) Developed for 5 minutes at 70 F. in the following solution:

Grams N-methyl-p-aminophenol hydrosulfate 5.0 Hydroquirione 31.4 Sodium sulfite 151.0 Potassiumcarbonate 104.3 Sodium hydroxide 6.6 Potassium bromide 11.7

Water to make 4 liters (2) Rinsed in water for 5 minutes, (3) Fixed for minutes at 70 C. in the following solution:

Grams Sodium thiosulfate 350.0 Sodium sulfite 15.0 Sodium acetate 18.0 Potassium aluminum sulfate 32.0

Citric acid 8.0 Water to make 1 liter I (4) The film was then washed in water for 10 minutes, tested for anchorage and the wet and dry anchorage was excellent.

Example 11 The entire procedure of Example I was repeated except that toluene-2,4-diisocyanate was substituted for the diisocyanate of that example. The results were similar.

Example III The entire procedure pf Example I was repeated except that the dimer of toluene 2,4-diisocyanate was substituted for the diisocyanate of that example. The results were similar.

Example IV A sample of polyethylene terephthalate film, having a melting point above 200 C., and an intrinsic viscosity of approximately 0.50 in a mixture of 2,4,6-trichlorophenol and phenol (70:100 parts by weight) was coated with an aqueous dispersion of a vinylidene chloride copolymer of the type described in U. S. Patent 2,627,088. After drying at 50 C., the film was stretched biaxially (3 times the original dimensions in both directions) and treated with a 1% solution of methylene bis[4-phenylisocyanate] in methylene chloride. After drying at 50 C., a solution of meta-(benZoyl-acetamido) benzaldehydesodiurn-o-sulfobenzaldehyde polyvinyl mixed acetal having the following composition was applied:

Percent Meta (benzoylacetamido)benzaldehyde sodium o-sulfobenzaldehyde-polyvinyl mixed acetal 1.5 Boric acid 1.9 Diisopropanolamine 1.3 Acetone 40.0 ethyl alcohol 55.3

(1) Developed for 10 minutes at 68 F. inthe following solution:

Grams Para-aminodiethylaniline hydrochloride 2.5 Sodium sulfite 10.0 Sodium carbonate 46.8 Potassium bromide 2.0

Waterto make 1 liter (2) Rinsed in water for 30 seconds, (3) Fixed for 5 minutes at 68 F. in the following solution:

. Grams Sodium thiosulfate 240.0 Sodium sulfite 15.0 Sodium 'tetraborate 18.0 Glacial acetic acid 12.0 Potassium aluminum sulfate 20.0

Water to make 3 liters (4) Rinsed in water for 5. minutes, (5) Bleached for 5 minutes at 68 F. in the following solution:

. Grams Potassium ferricyanide 100.0 Boric acid 10.0

I Sodium tetraborate 5.0

Water to make 1 liter. (6') Rinsed i'n wa'ter for 5 minutes, (7) Fixed for 5 minutes at 68 F. in the following solution:

Sodium thiosulfate -grams 200.0 Water to make 1 liter. (8) Rinsed in water for 10 minutes.

After the above exposing, processing and washing, the wet and dry anchorage was satisfactory.

Example 'V A sample of polyethylene terephthalate film base having-a melting point above 200 C., and an intrinsic viscoslty of 'approximately 0.50 infa mix'tur'e of 2,4,6-trichlorophenpl and phenol (70:100 parts by weight), was treate w t 1.11%, fs lu 10 et 'y e -D 'y lso'cyan'ate) "in methylene chloride, 'dried a't'50 'C., h'eated at 100 C. for 2 minutes and coated with a gelatinosilver halide emulsion. After exposing, developing, washing, fixing and washing in the manner described in Example I, the adhesion both wet and dry, was satisfactory.

Example VI A sample of polyethylene terephthalate film of the type described in Example V was treated as in Example V, except that the film had been biaxially stretched before the solution of methylene bis (4-phenylisocyanate) was applied. The results, after coating with a gelatino-silver halide emulsion, and processing as described in Example I, were similar.

Example VII A sample of biaxially stretched polyethylene terephthalate of the type described in Example V was treated with a solution of methylene bis (4-phenyl-isocyanate) as described in Example V. After drying, a gelatin dispersion of the following composition was applied over the diisocyanate layer:

I Percent Gelatin 1 Glacial acetic acid 4 Methanol 40 Acetone 55 The film, thus treated, was heated for 2 minutes at 100 C. and coated with a silver-gelatino halide emulsion. After exposing, developing, washing, fixing and washing, as described in Example I, the adhesion, wet and dry was found to be good.

Example VIII fobenzaldehyde-polyvinyl mixed acetal 1.5 Boric acid 1.9 Diisopropanolamin'e 1.3 Acetone 40.0 Ethyl alcohol (95%) 55.3

The film thus treated, was heated for 2 minutes at 100 C. and coated with a polyvinyl acetal color-former-silver halide emulsion containing 1.5% by weight of silver iodobromide comprised of approximately 1.3% silver iodide and 98.7% silver bromide, dispersed in the polymeric color former (3.8% by weight of the total emulsion) described in Martin U. S. Patent 2,513,190. After drying, the emulsion was found to have good adherence to the film base. It was exposed and processed in the following solutions:

(1) Developerfor 10 minutes at 68 F.

Grams p-Aminodiethylaniline hydrochloride 2.5 Sodium sulfite 10.0 Sodium carbonate 46.8 Potassium bromide 2.0 Water to make 1 liter. (2) Water rinse-for 30 seconds (3) Fixerfr minutes at 68 F.

- Sodium thiosulfate grams 240.0 Sodium sulfite do 15.0 Sodium tetraborate do 18.0 Glacial acetic acid cc 12.0 Potassium aluminum sulfate grams 20.0 Water to make 3 liters. (4) Water rinsefor 5 minutes (5) Bleach-for 5 minutes at 68 F.

' Grams Potassium ferricyanide 100.0 Boric acid 10.0 Sodium tetraborate 5.0 Water to make 1 liter. (6) Water rinse-for 5 minutes (7) Fixer--for 5 minutes at 68 F.

Sodium thiosulfate grams 200.0 Water to make 1 liter. (8) Water rinse for 10 minutes.

Example IX Example VII was repeated except that toluene 2,4-di

Example VII was repeated except that hexamethylene diisocyanate was substituted for the methylene bis (4- phenylisocyanate) of that example.

obtained.

Example XI Example VII was repeated except that the dimer of toluene-2,4-diisocyanate was substituted for the methylene bis (4-phenylisocyanate) of that example. Similar results were obtained.

It is apparent from the above that applicant has produced novel film elements by reason of the new anchoring substratum. The diisocyanate or diisothiocyanate layer is very thin and the remaining layers have their conventional thicknesses. In the case of the polyethylene terephthalate film bases with the vinylidene chlorideacrylic esteritaconic acid copolymer layer the thicknesses of the various layers may be as set forth in aforesaid Patent No. 2,627,088.

In place of the particular isocyanates described in the foregoing examples there may be substituted in similar amounts any of the polyisothiocyanates, polyisocyanates, diisothiocyanates, diisocyanates described above and below. Mixtures of any two or three or more of such cyanates can be used. Exemplary compounds include polymethylene diisocyanates and diisothiocyanates such as ethylene diisocyanate, trimethylene diisocyanate, do-' decamethylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, and the corresponding diisothiocyanates; alkylene diisocyanates and diisothiocyanates such as propylene 1,2- diisocyanate, 2,3-dimethyltetramethylene diisocyanate and diisothiocyanate, butylene-1,2-diisocyanate, butylene-1,3- diisothiocyanate, and butylene-l,3-diisocyanate; alkylidene diisocyanates and diisothiocyanates such as ethylidene diisocyanate (CH3CH(NCO)2) and heptylidene diisothiocyanate (CH3(CH2)5CH(CNS)2); cycloalkylene diisocyanates and diisothiocyanates such as 1,4-diisocyanatocyclohexane, cyclopentylene-1,3-diisocyanate, and cyclohexylene-1,2-diisothiocyanate; aromatic polyisocyanates and polyisothiocyanates such as m-phenylene diisothiocyanate, p-phenylene diisocyanate, p-phenylene diisothiocyanate, 1-methylphenylene-2,4-diisocyanate, naphthylene-1,4-diisocyanate, o,o'-toluene diisocyanate, diphenyl-4,4'-diisothiocyanate and diisocyanate, benzene- 1,2,4 triisothiocyanate, 5 nitro 1,3 phenylene diisocyanate, xylylene-l,4 diisocyanate, xylylene-1,3 diisocyanate, 4,4'-diphenylenemethane diisocyanate, 4,4'-diphenylenepropane diisocyanate and xylylene-1,4 diisothiocyanate; aliphatic-aromatic diisocyanates and diisothiocyanates such as phenylethylene diisocyanate (C5H6CH(NCO)CH2NCO); diisocyanates and' diisothiocyanates containing heteroatoms such as SCNCHzOCHzNSC SCNCHzCHzOCHzCHzNSC and 1,2,3,4-tetraisocyanatobutane, butane-1,2,2 triisocyanate,

l-isocyanato, 4-isothiocyanatohexane, and 2-chloro-1,3- diisocyanatopropane. Mixtures of two or more of such compounds can be used.

The preferred diisocyanates, diisothiocyanates and mixed isocyanate-isothiocyanates have the general formula ZCNRNCZ in which R is a divalent hydrocarbon radical and Z is a chalcogen of atomic weight less than 33. Suitable diisocyanate dimers are described in Kirkpatrick and Willett, N. S. app. Ser. No. 261,922, filed December 15, 1951.

In place of the specific solvent given in the examples one can use other solvents or mixtures of solvents for the cyanate compounds which have a slight solvent action on the particular film base and do not react with polyisocyanates or polyisothiocyanates. Such solvents include hydrocarbons, ethers, esters, and chlorinated hydrocarbons. The polyisocyanate or polyisothiocyanate can constitute from 0.10% to 10% and preferably 0.25% to 4.0% by weight of the solution. Among such additional useful Similar results were solvents are benzene, toluene, xylene hexane, heptane, dioxane, methylene chloride, chloroform,,trichlorethylene, tetrachlor'ethane, carbon tetrachloride, methyl acetate, ethyl acetate andmixtures of'two or more ofsuchs'o'lvents.

The heating period may vary considerably depending: on the particular temperature, colloid layer, colloid silver halide layer, etc. A practical period is from /2 minute tov 15minutes.

It: is to be understood that the. coating of the silver halide dispersions and subsequent drying, winding, slitting,

cutting, perforating operations, etc., described above,-are

to be carried out in the absence of'actinic light.

In place of the specific colloid silver-halide emulsions described in the foregoing examples there may becoated onto the layer of isocyanate compound various other colloid silver halide emulsion layers and water-permeable colloid sublayers free from light-sensitivesilver-halides. Thus among the additional colloids which can be anchored in accordance with the invention. are polyvinyl alcohols and water-soluble polyvinyl alcohol derivatives in general, e. g., partially hydrolyzed polyvinyl acetates, and mixed polyvinyl-chloride-acetatcs, hydrolyzed interpolymers of vinyl acetate with unsaturated compounds, for example, maleic anhydride, acrylic acid esters, etc. Suitable col loids of the last mentioned types are disclosed in United States Patents 2,276,322, 2,276,323 and 2,397,866 Still other colloids include hydrophilic partially substituted polyvinyl esters and acetals and the low substituted cellulose esters of saturated aliphatic monocarboxylic acids of 2 to 4 carbon atoms and low substituted cellulose ethers, e. g., methyl-cellulose, ethyl-cellulose, etc. Additional natural colloids include casein, albumin, gum arabic, agar agar, polyglycuronic acid, etc., which are also anchored to supports by these new substrata.

The invention can be used in the preparation of all types of photographic film elements including black and white and color films for motion picture and still photography, portrait film, document recording film, lithographic film, medical, dental and industrial X-ray .film, soundrecording film, films of the type described in Frankenburger et al. U. S. 2,180,409, stripping films'of the type described in Jennings U. S. Patent 2,462,503, etc.

An advantage of the invention is that it provides a simple and economical manner for improving the anchorage of water-permeable colloid silver halide emulsion layers to hydrophobic film bases. Another advantage is that the invention can be practiced with the conventional equipment of a photographic film manufacture. The invention enables one to obtain good anchorage between formaldehyde hardened gelatinosilver halide emulsions and a hydrophobic film base. A further advantage is that the invention enables one to obtain adequate anchorage to a hydrophobic film base that has been aged. The invention is particularly advantageous with the copolymer coated polyester film bases described above. Still other advantages will be apparent from the above description of the invention.

As many widely different embodiments of this invention can be made without departing from the' spirit and scope thereof, it is to be'understood that the'invention is not to be limited except as defined by the claims.

What is claimed is: e

1. A process which comprises coating an essentially anhydrous organic solvent solution containing an organic isocyanate compound taken from the group consisting of polyisocyanates and polyisothiocyanates onto a hydrophobic film base, drying the resulting layer, applying an aqueous solution containing a water-permeable colloid to the layer of isocyanate compound and drying the film element at a temperature from-50 (3.10

2. A process which comprises coating an essentially anhydrous organic solvent solution containing an organ c" polyisocyanate onto a hydrophobic film base, drying the resulting layer, applying an aqueous solution-containing a water-permeable colloid to the layer of polyisocyanate and heating the resulting element to a temperature from 50 C. to 150 C.

3. A process which comprises coating anessentially 8: anhydrous organic solvent solution; containing. an or-. ganic. polyisothiocyanate onto a hydrophobic'film base, drying the resulting layer, applying an aqueous solution. containing a water-permeable colloid to theplayer of; poly-. isothiocyanate and heating the resulting element to, a temperature from 50 C. to 150 C.

4. A process which comprises coating an essentially anhydrous organic; solven olu io con aining: an. rcmatie'diisocyanate. onto a hydrophobic film base, drying the r lt n v y r apply ng. n aqueo s. so ut on. @01 taining a. w t r-p rme b e coll i to; he ay r at dii o cyanate, and heating the resulting element; to. a tempera: ture from 50 C. to. 150 C.

5. A process which comprises coating an essentially anhydrous organic solvent solution containing an aromatic diisothiocyanate onto a hydrophobic film base, drying e. resulting laye pp y ng aque us olu n containing a water-permeable. Colloid to the layer of diisothiocyanate and heating the resulting element to a temperature from 50 C. to 150 C.

6;- A proc w ch omp i e a g an e sential y anhydrous volatile organic solvent solution containing an organic polyisocyanate onto a hydrophobic fihn base, dry the. r su ting. aye pp y n an aqueous. s lut on n ng. a ater-permeable col oid o a d. ay Qt s y n te mp un dry n the resultin aye atin an aqu ou d spersion of. li h -sensit ve il e ha des in a water-permeable. colloid onto said colloid layer and heating the resulting film element to a temperature from 50 C. to C.

7. A process which comprises coating an essentially anhydrous volatile organic solvent solution containing an aromatic diisocyanate onto a hydrophobic film base;

drying the resulting layer, coating an aqueous solution of gelatin onto the diisocyanate layer, drying the gelatin layer, applying a gelatino-silver-halide emulsion" layer to said gelatin layer and heating the resulting element to a temperature from 50 C. to 100 C., for a period of /2 tolS minutes.

8. A process which comprises coating an essentially anhydrous volatile organic solvent solution containing an aromatic diisocyana'te onto a hydrophobic film base, consisting of a polyethylene terephthalate film bearing a coating of a vinylidene chloride-acrylic ester-itaconi'c acid copolymer substratum, drying the resulting layer, coating an aqueous solution of gelatin onto the diisocyanate layer, drying the gelatin layer, applying a gelatino-silver-halide emulsion layer to said gelatin layer and heating the resulting element to a temperature from 50 C. to 100 C., fora period of /2 to 15 minutes.

9. A photographic film element comprising a hydrophobic film base, bearing in order on one surface a stratum composed of an organic isocyanate compound taken from the group consisting of polyisocyanates and pol isothiocyanates and at least one water-permeable col oid layer.

10. An'element as set forth in claim 9 wherein said colloid layer has uniformly dispersed therethrough lightsensitive silver halides.

11. A photographic element comprising a hydrophobic film base, bearing in order on one surface a stratum composed of an isocyanate compound taken from the group consisting of polyisocyanates and polyisothiocyanates, a. tayer of gelatin and a gelatino-silver-halideemulsion ayer.

12. An element as set forth in claim 11 wherein said film base is composed of a' polyethylene terephthalate film having a substratum composed of a vin'ylidenechloride-acrylic ester.-itaconic acid copolymer.

References Cited in the file of this patent UNITED STATES PATENTS 

6. A PROCESS WHICH COMPRISES COATING AN ESSENTIALLY ANHYDROUS VOLATILE ORGANIC SOLVENT SOLUTION CONTAINING AN ORGANIC POLYISOCYANATE ONTO A HYDROPHOBIC FILM BASE, DRYING THE RESULTING LAYER, APPLYING AN AQUEOUS SOLUTION CONTAINING A WATER-PERMEABLE COLLOID TO SAID LAYER OF ISOCYANATE COMPOUND, DRYING THE RESULTING LAYER, COATING AN AQUEOUS DISPERSION OF LIGHT-SENSITIVE SILVER HALIDES IN A WATER-PERMEABLE COLLOID ONTO SAID COLLOID LAYER AND HEATING THE RESULTING FILM ELEMENT TO A TEMPERATURE FROM 50* C. TO 100* C. 